Recently, communication networks have widely spread and are used by a continuously increasing number of subscribers. In order to cope with the increasing number of subscribers and correspondingly the increasing number of terminals of said subscribers which are potentially attached to the network for communication purposes, communication networks have to be most carefully planned in order that the network can be operated smoothly while meeting all requirements of the subscribers.
It is to be noted that the present invention is not limited to a specific type of communication network. It may be for example a wireless communication network such as the UMTS network or any other communication network. Also, network planning is to be understood as a process of setting network operating parameters such as transmit power, antenna characteristics, selection of transmitter sites and/or decision to install further transmitter sites. (A transmitter site in the example of a UMTS network means a Node_B (corresponding to a base station BS in GSM)). In order to effectively perform such a network planning, however, a most properly executed network performance analysis is required, since otherwise network planning would result in a mere “trial and error” process which is cumbersome and rather time consuming, and the success of which is doubtful and can not be verified quantitatively.
The requirements of the users to be met by the communication network can be deemed to be represented by the services the subscribers have subscribed to and among which they may select for communication purposes.
The definition of the term “service” as used herein is to be understood in its broadest sense and can, for example, be a PDP (Packet Data Protocol) context, while if the end user service (the actual application run on the terminal such as e.g. TCP/IP (Transmission Control Protocol/Internet Protocol) or voice call, SMS (Short Message Service), video conferencing) is known, also that can be used as definition of the service. More generally, a service is characterized by at least one service attribute, which is for example bit rate, BLER (service performance target) and Eb/No (energy per bit over noise) or a combination of these and/or others known in the field of communication networks. The main issue is that the definition of service is related to a set of at least one attribute and these attributes define the dimensions of the “information matrix” to be used. The mobile network has for example the following attributes concerning the “service”: The service performance target (BLER), Eb/No target, and/or the used bit rate. Also, the definition of service can be dependent on performance management (PM). PM is defining with what abstraction the service can be detected (UMTS traffic class (real-time, interactive, streaming, background) vs. the actual service (e.g. different real-time services distinguishable by used bit-rate) etc.)
Setting of network operating parameters in a way so as to improve and/or optimize the network performance requires a knowledge of the “behavior” of the network, in particular in downlink direction (from the transmitter stations to the terminals).
Traditionally the downlink direction information for optimization purposes has been very difficult to acquire. The only way to collect coverage related data has been with drive tests with field tool and this requires relatively lot manpower which makes data collection quite expensive and also time consuming. Furthermore, the field tool data has not been transferred to Network Management System (NMS) for further analysis and thus the coverage information is based either on planning tool (very inaccurate) or statistical “snapshots” based on drive tests in the network (these are in addition only related to a limited area of the network dependent on the number of drive tests conducted simultaneously).